DE2045087B2 - Process for the production of alkanesulfonic acids - Google Patents

Description

The invention relates to a process for the recovery of alkane sulfonic acids from a reaction mixture which has been obtained by settling in the sulfoxidation of alkanes with! 0 to ₅ 26 carbon atoms and after separation of a major portion of unreacted Alkauen.

Usually used as a surface-active agent! used Alkanesulfonic acids are usually produced by photosulfoxidation of alkanes.

According to the teachings of the German Olfenlegungsschrift 1518 854 are from a sulfoxydation mixture largely sulfuric acid-free alkanesulfonic acids obtained by being in a separator Aqueous phase of the reaction mixture obtained by settling is transferred to a high-speed evaporator and there by distillation from a small amount of unreacted alkane and one considerable amount of water is released. The liquid evaporation residue (from the Rapid evaporator) transferred to a separator and separated there in two phases. the the lower fraction obtained in this way consists of a concentrated aqueous sulfuric acid solution, the obtained upper fraction consists of a mixture of alkanesulfonic acid product and a substantial one Amount of unreacted alkane (see example 1 of the German Offenlegungsschrift 1518 854, fourth and third from last line).

By means of the method known from German Offenlegungsschrift 1 518 854, essentially the object can be achieved from the reaction mixture (without passing steam) a larger proportion of water to evaporate in order to concentrate the sulfuric acid contained in the reaction mixture in such a way that it later, when allowed to settle, as a lower layer in the form of a concentrated aqueous sulfuric acid solution can be separated.

In contrast, the invention was based on the object alkanesulfonic acids that are largely free from the sulfoxidation mixture of unreacted alkanes to win. This task can be accomplished by what is known from German Offenlegungsschrift 1,518,854 Measures do not solve, since the alkanesulfonic acids obtained by the known process only - in a separate reaction stage - of the larger amounts present as impurities unreacted alkanes would have to be freed.

The subject matter of the invention is thus a method of the type described at the outset, which is characterized is that the reaction mixture is steam distilled and then the sulfuric acid in on is removed in a known manner by settling.

Since in the process according to the invention the viscosity of the reaction mixture at the time the residual alkane is removed by steam distillation is lower than before, it can be used at a comparatively low temperature, ie usually at 80 to 250 ^° C. and a pressure of 50 to 760 mm Hg column and preferably at Perform 100 to HO ⁰ C and a pressure of 50 to 100 mm Hg column; In addition, the separation performance can also be increased on this occasion. In addition, this steam distillation at a comparatively lower temperature improves the color of the alkanesulfonic acids. Since one can also achieve simultaneous removal of sulfuric acid and sulfur dioxide in the inventive method, the heat level of performance is improved, and the calorie consumption reduced to about _^2/3 of recent needs. Table I below gives a comparison between the process according to the invention and the known process with regard to the separation of the unreacted alkane on the one hand and the sulfuric acid on the other hand. The separation is expediently carried out in such a way that the concentration of the sulfuric acid separated from the sulfoxidation mixture is 50 to 95, preferably 65 to 80 percent by weight.

Table I.

procedure new conditions known Separation of the unavoidable put alkanes 26th Output (n-alkane g / h) 11 Steam consumption (in grams per 3 Grams of n-alkane) 9 100 Temperature (in ⁰ C) 150 Color (KL color in 5% 250 aqueous sodium sulfonate solution) .. 400 Separation of the sulfuric acid 100 Temperature (in ° C) 140-150 Concentration of the ab different sulfuric acid 70 (in percent by weight) 65-70 Duration of acid deposition 10 (in min) 30th Acid separation (in weight 90 percent) 88

As already explained, a feature of the invention is that one - after discontinuing the Main part - the remaining amount of unreacted alkane at the same time as the sulfur dioxide Separates steam distillation from the reaction mixture. About the conditions of this distillation there the following table II information.

Table II

parameter mini-
mm area
Maxi-
mm optimum Reason for di
be
Mini
(mm) e limitation
ir.
Maxi
(mm) Distillation
temperature (in ⁰ C) 80 250 100-110 Distillation is
expensive Color deterioration
tion at the reac
tion product Distillation pressure
(in mm Hg) 50 760 50-100 Distillation and
Apparatus are closed
expensive Distillation is
expensive Concentration of
after the concentrate
tion severed
sulfuric acid 50 95 65-80 Acid deposition
rate is too low Color mismatch
tion at the reac
tion product

The drawing is a schematic representation of the system with which one embodiment of the Invention can work.

The invention of some preferred exemplary embodiments is explained in more detail below without referring to them to be limited.

example 1

30th

A reactor 1 was initially equipped with 51 of an n-AJVans charged and then via line 2 with 600 l of reaction gas per hour in the form of a sulfur dioxide-oxygen mixture in a mixing ratio of 2 to 1 volume and via line 4 or 5 with every hour 401 more n-alkane and additional water are filled each time, and by igniting a 100 W high-pressure mercury lamp photosulfoxidation was effected. The reaction product obtained in this way was transferred through line 6 to the separator tank 7, where it turns into unreacted n-alkane and a heavy mixture of 30 weight percent sulfonic acids, 30 weight percent Water, 10 percent by weight sulfuric acid, 28 percent by weight n-alkane and 2 percent by weight Split carbon dioxide. This heavy mixture was fed into the distillation tower 9 via line 8 of 5 cm in diameter and 30 cm in height, in which with the help of supplied through line 10, to 150 ° C superheated steam a steam distillation was carried out at 150 ° C, with the tower at the same time was heated from the outside. The distillate formed from n-alkane, water and sulfur dioxide was transferred through the line II into the separator tank 12, where it is in water that is passed through line 13 drained, in n-alkane, which was fed to the line 14, and divided into sulfur dioxide, which was via line 15 has been removed. The residue of sulfonic acids and 70 percent by weight remaining in the tower 9 Sulfuric acid was drawn off via line 16 and transferred to the separator tank 17, in which it is divided into sulfuric acid and sulfonic acid. The sulphonic acids produced here were transported via line 18 transferred to the neutralization tank 20, from which the alkanesulfonates are finally discharged via line 20 became.

In Table III below are the operating conditions and compiled the results of this experiment:

Table III

Work step conditions Result separation treated amount 26th by (n-alkane in g / h) distillation Amount of steam (in grams 3 per gram of n-alkane) Temperature (in ⁰ C) 150 Pressure (in mm Hg) 160 Withdrawal rate regarding 100 SO ₂ (in%) Separation of the Temperature (in ⁰ C) 150 sulfuric acid Concentration of the ab 70 different sulfur . acid (in weight percent) Time required for the 10 trennang (in minutes) Separation rate (in%) 90 properties Sulfonic acid content 80 the ab (in percent by weight) divorced n-alkane content (in Ge 0.5 Sulfonic acid weight percent) Sulfuric acid content 2.7 (in percent by weight) Water content (in Ge 16.8 weight percent) Sulfur dioxide content only trace (in percent by weight) Color (KL color in 400 5 ° more aqueous Na sulfonate solution)

Example 2

Example 1 was repeated with the modification that the steam distillation in tower 9 at only 130.degree with steam superheated to 130 ° C and with external heating was carried out and that the residue flowing off via line 16 in relation to sulfuric acid was only 65%.

The implementation conditions for this experiment and the results obtained with it are shown in the following Table IV can be seen.

5 Table IV

Work step conditions Result separation treated amount 22nd by (n-alkane in g / h) distillation Amount of steam (in grams 7.5 per gram of n-alkane) Temperature (in ⁰ C) 130 Pressure (in mm Hg) 760 Withdrawal rate regarding 100 SO ₂ (in%) Separation of the Temperature (in ⁰ C) 130 sulfuric acid Concentration of the ab 65 different sulfur acid (in weight percent) Time required for the Ab 10 separation (in minutes) Separation rate (in%) 80 properties Sulfonic acid content 70 the ab (in percent by weight) divorced n-alkane content 0.5 Sulfonic acid (in percent by weight) Sulfuric acid content 4.7 (in percent by weight) Water content 24.8 (in percent by weight) Sulfur dioxide content only trace (in percent by weight) Color (KL color in 300 5% aqueous Na sulfate solution)

Work step IO conditions Result S properties Sulfonic acid content 80 the ab (in percent by weight) divorced n-alkane content 0.4 Sulfonic acid ■ 5 (in percent by weight) Sulfuric acid content 2.5 (in percent by weight) Water content (in Ge 17.1 weight percent) Sulfur dioxide content only trace (in percent by weight) Color (KL color in 300 5% aqueous Na sulfonate solution)

Example 4 Example 1 was repeated with the modification

that the distillation tower under external heating with au

110 ⁰ C superheated steam charged and on a r

Internal pressure of 100 mmHg was maintained. From

The sulfuric acid flowing off the tower was 70%.

In Table VI below, the implementation conditions and the results of this Ver such a compilation.

Table VI Example 3

Example 1 was repeated with the modification that the distillation tower with external heating with only 100 ° C hot steam was charged and kept at an internal pressure of only 50 mm Hg. The ones from the Sulfuric acid flowing off the tower was 70% strength.

In Table V below are the operating conditions and the results of this experiment compiled

Table V

Work step conditions Result separation treated amount 27 by (n-alkane in g / h) distillation Amount of steam (in grams 3.5 per gram of n-alkane) Temperature (in "C) 100 Pressure (in mm Hg) 100 Withdrawal rate regarding 50 SO ₂ (in%) Separation of the Temperature (in ° C) 100 sulfuric acid Concentration of the ab 70 different sulfur acid (in weight percent) Time required for the Ab 10 separation (in minutes) Separation rate (in%) 90

Work step

separation

by

distillation

Separation of the sulfuric acid

properties the separated Sulfonic acid

conditions

treated amount (n-alkane in g / h)

Amount of steam (in grams

per gram of n-alkane) Temperature (in ⁰ C) Pressure (in mm Hg)

Withdrawal rate regarding SO ₂ (in%)

Temperature (in ° C)

Concentration of the separated sulfuric acid (in percent by weight)

Time required for separation (in minutes)

Separation rate (in%)

Sulfonic acid content (in percent by weight)

n-alkane content (in percent by weight)

Sulfuric acid content (in percent by weight)

Water content (in percent by weight)

Sulfur dioxide content (in percent by weight)

Color (KL color in 5% aqueous Na sulfonate solution)

Result

110 100 100

110 70

250 lane only

Comparative example

The reaction mixture obtained according to Example 1 was this time worked up in the following way:

It was heated first to remove sulfur dioxide and then again to concentrate the sulfuric acid it contained. After removing the thus concentrated sulfuric acid from it, it was then neutralized and then transferred to the distillation tower 9, where it was subjected to steam distillation. The result of this Attempts to remove n-alkanes are shown in Table VII below.

Table VII Work step

SO ₂ removal by heating

Sulfuric acid concentration

Condition.

Temperature (in ⁰ C) withdrawal rate (in%)

Temperature (in ⁰ C) Concentration of the separated sulfuric acid (in percent by weight)

Result

100 100

Work step

Sulfuric acid separation by settling

(Alkane) distillation

Properties, _{s of} the deposited sodium sulfonate

140-150 65-7Q

conditions

Time required for separation (in minutes) Separation rate (in%)

treated amount (n-alkane in g / h)

Temperature (in "C) Amount of steam (in grams] per gram of n-alkane)

Na sulfonate content (in percent by weight)

Na sulfate content (in percent by weight)

n-alkane content (in percent by weight)

Water content (in percent by weight)

Paint (KL paint in 5% aqueous Na sulfonate solution)

Result

30th

88 11

150 9

60 3.5 0.5 36 400

1 sheet of drawings

4095ΠΜ26

Claims (1)

Claim: Process for the production of alkali sulfonic acids from a reaction mixture that occurs in the sulfoxidation of AJkanen with 10 to 26 carbon atoms and after separating a larger part of unreacted alkanes by settling has been obtained, characterized in that that the reaction mixture is steam distilled and then the sulfuric acid is removed in a manner known per se by settling